The present invention relates to a method and apparatus for receiving discrete parts of a workpiece traveling at different speeds relative to one another and applying the parts to a moving web of material. More particularly, the invention concerns a method and apparatus for receiving discrete parts from at least two webs of moving material moving at different speeds and depositing the discrete parts with controllable registration on a third continuously moving web of material.
Articles such as infant diapers, adult continence diapers, feminine napkins and the like have been manufactured generally by processes where discrete parts or components of the article are deposited on a continuously moving product web. Often, the speed with which the parts or components are produced and fed into the process is not the same as the speed of advance of the product web itself. In such cases, the speed of production and/or deposition of the component parts on the moving web must be varied to match the speed of the product web to properly match the parts to the moving web without adversely affecting the process or finished article.
Several methods for changing the speed of a part or component of material for deposition on a continuously moving web are known in the art. One method employs rollers segmented into sections which are inwardly and outwardly moveable in a direction radial to their direction of rotation. As the roller rotates, the segments are driven by cam actuating or gearing means to move inwardly and outwardly changing the linear surface speed of the roller segments as the roller rotates through each revolution.
Another method utilizes festoons to reduce the speed of the moving web to which the parts or components are to be applied. The continuously moving web is temporarily slowed to the speed of the component parts to be deposited, with the excess portion of the continuously moving web gathering in festoons. While the continuously moving web is slowed to match the speed of the component parts, the parts are transferred to the web and the speed of the web is then accelerated to gather the festoons prior to the next cycle.
Another method is the so-called xe2x80x9cslip gapxe2x80x9d method in which the parts or components are cut from a web of material moving at a slower speed than the product web. As the component parts are cut from the first web of material, they are held to either the anvil roller or the cutter roller by means of vacuum. As the pieces pass tangentially to the continuously moving product web which is moving at a different speed, the parts or components slip temporarily until they are vacuum transferred to the continuously moving product web.
These known methods of transferring component parts, moving at one speed, to a continuously moving web moving at a different speed, do not address the problem of insuring careful registration of the deposited component parts on the continuously moving web. The problem is exacerbated when the need exists for depositing two or more components, one on top of the other on the continuously moving web while insuring careful registration of one component to the other, or to the moving web.
In one embodiment, the present invention provides a process for manufacturing a multi-component workpiece comprising at least two components cut from moving webs of material, registering the components with respect to one another, and depositing the registered components with on a web of moving material. The process comprises the steps of a) cutting the first discrete workpiece components from a web of first material moving at first web speed, b) cutting the second discrete workpiece components from a web of second material moving at a second web speed, c) mating the first and second discrete workpiece components and registering them with respect to one another, and d) depositing the mated first and second workpiece components with registration on a third web of material moving at a third constant speed.
In another embodiment, the invention provides a machine for cutting first and second discrete workpiece components, respectively, from first and second webs of material running at different constant web speeds, the first and second workpiece components being optionally of different lengths, registering them with respect to one another, and depositing them with registration on a third web of material moving at a third constant web speed.
The machine comprises a first apparatus for cutting discrete components from a web of material moving at a first web speed, and a second apparatus for cutting discrete components of a second material from a web of second material moving at a second web speed. Speed matching apparatus comprises a first speed matching roller for receiving first discrete workpiece components from the first cutting apparatus and a second speed matching roller for receiving second discrete workpiece components from the second cutting apparatus, and mating and registering the first and second workpiece components with respect to one another and depositing them with registration on the third web of material moving at a third constant speed.
Non-constant drive means drives the first and second speed matching rollers independently, each at a higher constant dwell speed and a lower constant dwell speed with appropriate periods of acceleration and deceleration between the higher and lower constant dwell speeds. One of the higher or lower constant dwell speeds of the first speed matching roller matches the constant speed of the third web material, and the other of the higher or lower constant dwell speeds of the first speed matching roller matches the constant web speed of the first web material. One of the higher or lower constant dwell speeds of the second speed matching roller matches the constant speed of the first web material, and the other of the higher or lower constant dwell speeds of the second speed matching roller matches the constant web speed of the second web material.
In another embodiment, the present invention provides a method of manufacturing a multi-component absorbent personal hygiene article comprising a distribution or wicking component layer, a fluid transfer delay component layer, and an absorbent layer, deposited on a backing layer, the distribution, fluid retaining and absorbent layers being of different length and positionally registered with respect to one another on the backing layer.